WO2022202034A1

WO2022202034A1 - Ultrasonic probe

Info

Publication number: WO2022202034A1
Application number: PCT/JP2022/006899
Authority: WO
Inventors: 敦大澤
Original assignee: 富士フイルム株式会社
Priority date: 2021-03-26
Filing date: 2022-02-21
Publication date: 2022-09-29
Also published as: JPWO2022202034A1; EP4319196A1; US20230414200A1

Abstract

An ultrasonic probe 1 in which a plurality of piezoelectric elements (3) are arrayed on a backing material along an array direction. The ultrasonic probe (1) comprises a plurality of acoustic matching layers (4, 5, 6, 7) stacked on respective ones of the piezoelectric elements (3), wherein at least one acoustic matching layer (4) among the plurality of acoustic matching layers (4, 5, 6, 7) is composed of at least one acoustic matching piece (4A, 4B) having a width narrower than the width of the piezoelectric elements (3) in the array direction.

Description

ultrasonic probe

The present invention relates to an ultrasonic probe used for ultrasonic examination of a subject.

　Conventionally, ultrasonic examination is known in which a subject is examined by confirming an ultrasonic image representing an image of the inside of the subject. Ultrasound images are obtained by transmitting ultrasound beams into the subject using an ultrasound probe that includes a transducer array in which a plurality of piezoelectric elements are arranged, and capturing ultrasonic echoes propagating from within the subject with the ultrasound probe. to obtain an electrical signal and electrically process the electrical signal.

In recent years, so-called POC (Point of Care) ultrasound examinations are often performed to support the treatment of subjects. In POC, it is desired to observe fine structures such as muscle structures and nerve bundles of a subject. In response to such demands, for example, as disclosed in Patent Document 1, in order to obtain a high-definition ultrasonic image by broadening the frequency band of ultrasonic waves used for forming an ultrasonic image, a plurality of acoustic matching Ultrasound probes with layers have been developed.

JP 2016-192666 A

By the way, as disclosed in Patent Literature 1, when a plurality of acoustic matching layers are arranged in an ultrasonic probe, there is a need to easily transmit ultrasonic waves between the piezoelectric element and the subject. In particular, the acoustic matching layer placed near the piezoelectric element is required to have a sufficiently high acoustic impedance.

For example, the acoustic impedance of the acoustic matching layer can be increased by forming the acoustic matching layer from a material with a high sound velocity. There is a problem that the frequency approaches the resonance frequency in the thickness direction of the piezoelectric element, and the image quality of the generated ultrasonic image deteriorates.

The present invention has been made in order to solve such conventional problems. The object is to provide a probe.

To achieve the above object, an ultrasonic probe according to the present invention is an ultrasonic probe in which a plurality of piezoelectric elements are arranged on a backing material along an arrangement direction, and each piezoelectric element a plurality of acoustic matching layers laminated on the It is characterized by

At least one acoustic matching layer is preferably the acoustic matching layer closest to the piezoelectric element among the plurality of acoustic matching layers.
The plurality of acoustic matching layers can be composed of four or more acoustic matching layers in which the acoustic impedance decreases stepwise as the distance from the piezoelectric element increases.

The resonance frequency in the width direction of the acoustic matching piece is preferably higher than the frequency on the high frequency side in the frequency band having at least half the amplitude value of the resonance frequency in the thickness direction of the piezoelectric element.
Further, it is more preferable that the resonance frequency in the width direction of the acoustic matching piece is higher than the frequency on the high frequency side in the frequency band having a value of 1/10 of the amplitude value of the resonance frequency in the thickness direction of the piezoelectric element.

At least one acoustic matching layer preferably comprises a plurality of acoustic matching pieces arranged in the arrangement direction.
At least one acoustic matching layer can be composed of a plurality of acoustic matching pieces arranged in the arrangement direction and in a direction orthogonal to the arrangement direction.
Also, the acoustic matching piece can have any one of a polygonal prism, a cylinder, a polygonal pyramid and a conical shape extending in the stacking direction of the plurality of acoustic matching layers.
Also, a filler made of resin can be arranged between the plurality of acoustic matching pieces.

According to the present invention, an ultrasonic probe includes a plurality of acoustic matching layers laminated on respective piezoelectric elements, and at least one acoustic matching layer among the plurality of acoustic matching layers comprises an array of piezoelectric elements Since it is composed of at least one acoustic matching piece having a width narrower than the width in the direction, it is possible to obtain a high-quality ultrasound image while broadening the frequency band of the ultrasound used to generate the ultrasound image.

1 is a cross-sectional view of an ultrasonic probe according to an embodiment of the present invention; FIG. 1 is a perspective view of a first acoustic matching layer according to an embodiment of the invention; FIG. FIG. 4 is a diagram schematically showing a frequency band including a resonance frequency caused by the frequency band of the piezoelectric element and the width of the acoustic matching piece of the first acoustic matching layer in the embodiment of the present invention; 1 is a block diagram showing the configuration of an ultrasonic diagnostic apparatus having an ultrasonic probe according to an embodiment of the present invention; FIG. 2 is a block diagram showing the internal configuration of a transmission/reception circuit according to an embodiment of the present invention; FIG. 3 is a block diagram showing the internal configuration of an image generator in the embodiment of the present invention; FIG. FIG. 4 is a perspective view of a first acoustic matching layer in a first modified example of the embodiment of the invention; FIG. 11 is a perspective view of a first acoustic matching layer in a second modified example of the embodiment of the invention; It is a top view of the 1st acoustic matching layer in the 3rd modification of an embodiment of the invention. It is a top view of the 1st acoustic matching layer in the 4th modification of embodiment of this invention. It is a top view of the 1st acoustic matching layer in the 5th modification of an embodiment of the invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
The description of the constituent elements described below is based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.
In this specification, a numerical range represented by "-" means a range including the numerical values before and after "-" as lower and upper limits.
As used herein, the terms "same" and "same" shall include the margin of error generally accepted in the technical field.

Embodiment As shown in FIG. 1, an ultrasonic probe 1 according to an embodiment of the present invention includes a backing material 2 and a plurality of piezoelectric elements 3 arranged on the backing material 2 for emitting ultrasonic waves. , a first acoustic matching layer 4 arranged on each of the plurality of piezoelectric elements 3, a second acoustic matching layer 5 arranged on the first acoustic matching layer 4, and a second acoustic matching A third acoustic matching layer 6 disposed on the layer 5, a fourth acoustic matching layer 7 disposed on the third acoustic matching layer 6, and a plurality of fourth acoustic matching layers 7 and an acoustic lens 8 formed by

Between adjacent piezoelectric elements 3, between adjacent first acoustic matching layers 4, between adjacent second acoustic matching layers 5, between adjacent third acoustic matching layers 6, and between adjacent fourth acoustic matching layers A separation portion filled with a filler SP made of resin such as epoxy resin is formed between 7 .

Also, the first acoustic matching layer 4 has two acoustic

matching pieces

4A and 4B each having a width narrower than the width of the piezoelectric elements 3 in the arrangement direction of the piezoelectric elements 3 .

Here, for clarity of explanation, the arrangement direction (azimuth direction) of the piezoelectric elements 3 is called the Y direction, the depth direction (elevation direction) of the piezoelectric elements 3 is called the X direction, and the backing material 2 and the piezoelectric The stacking direction of the element 3, the first acoustic matching layer 4, the second acoustic matching layer 5, the third acoustic matching layer 6, the fourth acoustic matching layer 7 and the acoustic lens 8 is called the Z direction.

Lead electrodes (not shown) are connected to the plurality of piezoelectric elements 3, respectively, and a flexible printed circuit board (not shown) connected to the lead electrodes is arranged on the side surface of the backing material 2 or the like, but is omitted for the sake of explanation. It is

The piezoelectric element 3 generates ultrasonic waves according to drive signals supplied from a pulser or the like (not shown) connected to the ultrasonic probe 1, receives ultrasonic echoes, and outputs signals based on the ultrasonic echoes. It is a thing. The piezoelectric element 3 is, for example, a piezoelectric ceramic typified by PZT (Lead Zirconate Titanate), a polymeric piezoelectric element typified by PVDF (Poly Vinylidene Di Fluoride), and PMN-PT ( Lead Magnesium Niobate-Lead Titanate: a solid solution of lead magnesium niobate-lead titanate). Moreover, the piezoelectric element 3 has a width of about 100 μm to 200 μm in the Y direction.

The backing material 2 supports the plurality of piezoelectric elements 3 and absorbs the ultrasonic waves emitted from the plurality of piezoelectric elements 3 and propagated backward. The backing material 2 is made of, for example, a rubber material such as ferrite rubber.

The acoustic lens 8 is in contact with the body surface of the subject during ultrasonic diagnosis and serves to converge the ultrasonic waves emitted from the plurality of piezoelectric elements 3, and is made of epoxy resin, acrylic resin, or polymethylpentene resin. It is formed from a resin material such as a rubber material such as silicone rubber.

The first acoustic matching layer 4 to the fourth acoustic matching layer 7 respectively match stepwise the acoustic impedance between the subject with which the ultrasonic probe 1 is in contact and the piezoelectric element 3, and the subject This is for making it easier for ultrasonic waves to enter inside. The first acoustic matching layer 4 to the fourth acoustic matching layer 7 are made of resin material such as epoxy resin or urethane resin.

As shown in FIG. 2, the acoustic

matching pieces

4A and 4B of the first acoustic matching layer 4 have a plate shape parallel to the XZ plane, and are arranged adjacent to each other and spaced apart in the Y direction. It is The acoustic matching piece 4A has a width L1 in the Y direction, and the acoustic matching piece 4B has a width L2 in the Y direction. The width L1 of the acoustic matching piece 4A and the width L2 of the acoustic matching piece 4B are each narrower than the width of the piezoelectric element 3 in the Y direction.

Also, the acoustic matching

pieces

4A and 4B of the first acoustic matching layer 4 are composed of the material forming the second acoustic matching layer 5, the material forming the third acoustic matching layer 6, and the fourth acoustic matching layer 7. It is made of a material having a higher acoustic impedance than the constituent material and a lower acoustic impedance than the piezoelectric element 3 .

Here, it is generally known that the acoustic impedance of a medium is represented by the product of the density of the medium and the speed of sound in the medium. Materials with relatively high acoustic impedances refer to materials with relatively low sound velocities.

In addition, the second acoustic matching layer 5 has a higher acoustic impedance than the material forming the third acoustic matching layer 6 and the material forming the fourth acoustic matching layer 7, and are made of a material having an acoustic impedance lower than that of the material forming the acoustic matching

pieces

4A and 4B.

The third acoustic matching layer 6 is made of a material having a higher acoustic impedance than the material forming the fourth acoustic matching layer 7 and a lower acoustic impedance than the second acoustic matching layer 5. .
The fourth acoustic matching layer 7 is made of a material having an acoustic impedance higher than that of the subject and lower than that of the third acoustic matching layer 6 .

In this way, the acoustic impedance is lowered stepwise in the order of the piezoelectric element 3, the first acoustic matching layer 4, the second acoustic matching layer 5, the third acoustic matching layer 6 and the fourth acoustic matching layer 7. That is, the first acoustic matching layer 4 to the fourth acoustic matching layer 7 are designed so that the acoustic impedance decreases stepwise as the distance from the piezoelectric element 3 increases.

In the ultrasonic probe 1 of the embodiment, the acoustic lens 8 is in contact with the body surface of the subject, and ultrasonic waves generated from the plurality of piezoelectric elements 3 by a driving voltage from a pulser or the like (not shown) are applied to the subject. By converting the ultrasonic echoes reflected by the tissues in the subject into electrical signals with a plurality of piezoelectric elements 3 and electrically processing the obtained electrical signals using an external device Used to generate ultrasound images.

Ultrasonic waves generated by the piezoelectric element 3 pass through the first acoustic matching layer 4, the second acoustic matching layer 5, the third acoustic matching layer 6, the fourth acoustic matching layer 7, and the acoustic lens 8 to the subject. sent within. Further, ultrasonic echoes propagated from inside the subject toward the ultrasonic probe 1 pass through the acoustic lens 8, the fourth acoustic matching layer 7, the third acoustic matching layer 6, and the second acoustic matching layer 5. and the first acoustic matching layer 4 to enter the piezoelectric element 3 , and the incident ultrasonic echo is converted into an electric signal by the piezoelectric element 3 .

In the ultrasonic probe 1, the four acoustic matching layers of the first acoustic matching layer 4 to the fourth acoustic matching layer 7 are arranged so that the acoustic impedance gradually decreases from the piezoelectric element 3 side to the acoustic lens 8 side. Since the layers are arranged, for example, even if the frequency of the ultrasonic waves emitted from the piezoelectric element 3 is sufficiently high, the ultrasonic waves are likely to pass through between the piezoelectric element 3 and the acoustic lens 8, resulting in an ultrasonic image. The frequency band of ultrasonic waves used for formation can be broadened.

Here, the frequency band of ultrasonic waves used for generating an ultrasonic image includes a resonance frequency caused by the thickness of the piezoelectric element 3 in the Z direction. It changes like band A1.

Usually, when trying to arrange a plurality of acoustic matching layers in order to broaden the frequency band A1, the acoustic impedance between the subject with which the ultrasonic probe 1 is in contact and the piezoelectric element 3 is matched. In particular, the acoustic matching layer arranged near the piezoelectric element 3 must be made of a material with high acoustic impedance. Assuming that the acoustic matching layer made of a material having a high acoustic impedance consists of one acoustic matching piece and that its Y-direction width is substantially the same as the Y-direction width of the piezoelectric element 3, as shown in FIG. Moreover, the frequency band A2 including the resonance frequency caused by the width of the acoustic matching layer in the Y direction may overlap with the frequency band A1 of the piezoelectric element 3 .

A sensitivity of, for example, −20 dB is often used when generating high-definition ultrasound images for observing fine structures such as muscle structures and nerve bundles of a subject. If the frequency band A1 of No. 3 overlaps with the frequency band A2 resulting from the width of the acoustic matching layer in the Y direction, the image quality of the generated ultrasonic image deteriorates due to the frequency band A2.

Since the acoustic matching piece 4A in the present embodiment has a width L1 that is narrower than the width of the piezoelectric element 3 in the Y direction, the resonance frequency due to the width L1 of the acoustic matching piece 4A is It is higher than the resonance frequency when it is assumed that the width of the element 3 is the same as the width in the Y direction. Therefore, by adjusting the width L1 of the acoustic matching piece 4A, the resonance frequency caused by the width L1 of the acoustic matching piece 4A can be adjusted to the sensitivity of −20 dB or the like used for generating a high-definition ultrasonic image. A frequency band A3 that does not overlap with the frequency band A1 can be obtained by setting the frequency higher than the frequency on the high frequency side in the frequency band A1.

Also, the acoustic matching piece 4B arranged adjacent to the acoustic matching piece 4A in the Y direction has a width L2 narrower than the width of the piezoelectric element 3 in the Y direction. The resonance frequency is higher than the resonance frequency when it is assumed that the acoustic matching piece 4B has the same width as the piezoelectric element 3 in the Y direction. Therefore, by adjusting the width L2 of the acoustic matching piece 4B in the same manner as the acoustic matching piece 4A, the width L1 of the acoustic matching piece 4B can be adjusted to the sensitivity of −20 dB or the like used for generating a high-definition ultrasonic image. It is possible to obtain a frequency band that does not overlap with the frequency band A1 by making the resulting resonance frequency higher than the frequency on the high frequency side in the frequency band A1 of the piezoelectric element 3 .

In this way, the first acoustic matching layer 4 includes an acoustic matching piece 4A having a width L1 narrower than the width of the piezoelectric element 3 in the Y direction and an acoustic matching piece 4A having a width L2 narrower than the width of the piezoelectric element 3 in the Y direction. Even if the

acoustic matching pieces

4A and 4B are made of a material with a sufficiently high acoustic impedance, the frequency band of the piezoelectric element 3 is limited by the sensitivity used to generate the ultrasonic image. A1 and the frequency band A3 caused by the width L1 of the acoustic matching piece 4A can be separated from each other, and the frequency band A1 of the piezoelectric element 3 and the frequency band caused by the width L2 of the acoustic matching piece 4B can be separated from each other.

From the above, according to the ultrasonic probe 1 of the embodiment, it has a plurality of acoustic matching layers of the first acoustic matching layer 4 to the fourth acoustic matching layer 7, and the first acoustic matching layer 4 is , the acoustic matching piece 4A having a width L1 narrower than the width of the piezoelectric element 3 in the Y direction and the acoustic matching piece 4B having a width L2 narrower than the width of the piezoelectric element 3 in the Y direction. It is possible to obtain a high-quality ultrasound image while widening the frequency band A1 used to generate .

Next, the ultrasonic diagnostic apparatus 11 having the ultrasonic probe 1 according to the embodiment of the invention will be described. As shown in FIG. 4, in an ultrasonic diagnostic apparatus 11, a transmitting/receiving section 12, an image generating section 13, a display control section 14 and a monitor 15 are connected to an ultrasonic probe 1 in this order. A device control unit 16 is connected to the transmission/reception unit 12 , the image generation unit 13 and the display control unit 14 . An input device 17 is also connected to the device control section 16 . A memory (not shown) is connected to the device controller 16 .
The ultrasonic diagnostic apparatus 11 also includes an ultrasonic probe 21 including the ultrasonic probe 1 . A processor 22 for the ultrasonic diagnostic apparatus 11 is configured by the transmitting/receiving section 12 , the image generating section 13 , the display control section 14 and the device control section 16 .

Under the control of the device control unit 16, the transmission/reception unit 12 transmits ultrasonic waves from the ultrasound probe 1 and generates sound ray signals based on the reception signals acquired by the ultrasound probe 1. As shown in FIG. 5, the transmitting/receiving section 12 includes a pulser 31 connected to the ultrasonic probe 1, an amplifier section 32 sequentially connected in series from the ultrasonic probe 1, and an AD (Analog Digital) conversion section. 33 and a beamformer 34 .

The pulsar 31 includes, for example, a plurality of pulse generators, and based on a transmission delay pattern selected according to a control signal from the device control unit 16, from the plurality of piezoelectric elements 3 of the ultrasonic probe 1 Each drive signal is supplied to the plurality of piezoelectric elements 3 after adjusting the delay amount so that the ultrasonic waves to be transmitted form ultrasonic beams. Thus, when a pulse-like or continuous-wave voltage is applied to the electrodes of the piezoelectric elements 3, the piezoelectric elements 3 expand and contract, and pulse-like or continuous-wave ultrasonic waves are generated from the respective piezoelectric elements 3. An ultrasonic beam is formed from the composite wave of ultrasonic waves.

The transmitted ultrasonic beams are reflected, for example, by tissues within the subject, and propagate toward the ultrasonic probe 1 of the ultrasonic probe 21 . Each piezoelectric element 3 of the ultrasonic probe 1 expands and contracts by receiving the ultrasonic echoes propagating toward the ultrasonic probe 1 in this way, and generates a reception signal which is an electric signal. , and outputs these received signals to the amplifier 32 .

The amplification section 32 amplifies the signal input from each piezoelectric element 3 of the ultrasound probe 1 and transmits the amplified signal to the AD conversion section 33 . The AD converter 33 converts the signal transmitted from the amplifier 24 into digital received data and transmits the received data to the beamformer 34 . The beamformer 34 converts each reception data converted into digital data by the AD converter 33 according to the sound velocity or the distribution of the sound velocity set based on the reception delay pattern selected according to the control signal from the device controller 16. A so-called reception focus process is performed by giving respective delays and adding them. By this reception focusing process, each reception data converted by the AD conversion unit 33 is phased and added, and an acoustic ray signal in which the focus of the ultrasonic echo is narrowed down is acquired.

As shown in FIG. 6, the image generator 13 has a configuration in which a signal processor 35, a DSC (Digital Scan Converter) 36, and an image processor 37 are connected in series.
The signal processing unit 35 performs envelope detection processing on the acoustic ray signal generated by the beamformer 34 of the transmitting/receiving unit 12 after performing attenuation correction due to distance according to the depth of the reflection position of the ultrasonic wave. generates a B-mode image signal, which is tomographic image information regarding tissues in the subject.

The DSC 36 converts (raster-converts) the B-mode image signal generated by the signal processing unit 35 into an image signal conforming to the normal television signal scanning method.
The image processing unit 37 performs various necessary image processing such as gradation processing on the B-mode image signal input from the DSC 36 , and then outputs the B-mode image signal to the display control unit 14 . In the present invention, the B-mode image signal subjected to image processing by the image processing unit 37 is simply referred to as an ultrasound image.

Under the control of the device control unit 16 , the display control unit 14 performs predetermined processing on the ultrasonic image generated by the image generation unit 13 and displays the ultrasonic image on the monitor 15 .
The monitor 15 displays the ultrasonic image generated by the image generation unit 13 under the control of the display control unit 14. For example, the monitor 15 displays an LCD (Liquid Crystal Display) or an organic EL display (Organic Electroluminescence Display). ) and other display devices.

The apparatus control section 16 controls each section of the ultrasonic diagnostic apparatus 11 based on a pre-stored control program or the like.
The input device 17 is for a user to perform an input operation, and can be configured by including a keyboard, mouse, trackball, touch pad, touch panel, and the like.

Although not shown, the memory connected to the device control unit 16 stores the control program of the ultrasonic diagnostic device 11 and the like. Solid State Drive), FD (Flexible Disc), MO disc (Magneto-Optical disc), MT (Magnetic Tape), RAM (Random Access Memory) , CD (Compact Disc), DVD (Digital Versatile Disc), SD card (Secure Digital card), USB memory (Universal Serial Bus memory), etc. , or a server or the like can be used.

In addition, the processor 22 having the transmission/reception unit 12, the image generation unit 13, the display control unit 14, and the device control unit 16 is a CPU (Central Processing Unit), and controls for causing the CPU to perform various processes. Program consists of FPGA (Field Programmable Gate Array), DSP (Digital Signal Processor), ASIC (Application Specific Integrated Circuit), GPU (Graphics Processing Unit) : graphics processing unit), other ICs (Integrated Circuits), or may be configured by combining them.

Also, the transmitting/receiving section 12, the image generating section 13, the display control section 14, and the device control section 16 of the processor 22 can be partially or wholly integrated into one CPU or the like.

Since the ultrasonic diagnostic apparatus 11 according to the embodiment of the present invention includes the ultrasonic probe 1 according to the embodiment of the present invention, the transmitting/receiving unit 12 transmits from the ultrasonic probe 1 to the subject. While broadening the frequency band of the ultrasonic waves received by the ultrasonic probe 1 and the frequency band of the ultrasonic waves received by the ultrasonic probe 1, a high-quality ultrasonic image can be obtained.

As shown in FIG. 1, between adjacent piezoelectric elements 3, between adjacent first acoustic matching layers 4, between adjacent second acoustic matching layers 5, between adjacent third acoustic matching layers 6, and between adjacent As the filler SP filled between the matching fourth acoustic matching layers 7, for example, silicon resin such as RTV630 manufactured by Momentive, epoxy resin such as EpoteK310M manufactured by Epoxy Technology, urethane resin, or the like can be used.

Also, the space between the acoustic matching piece 4A and the acoustic matching piece 4B arranged adjacent to each other in the first acoustic matching layer 4 can be filled with a filler similar to the filler SP. This prevents the acoustic matching piece 4A and the acoustic matching piece 4B from coming into contact with each other for some reason, so that the

acoustic matching pieces

4A and 4B can be arranged more stably.

The materials constituting the first acoustic matching layer 4 to the fourth acoustic matching layer 7 are not particularly limited. A material obtained by kneading oxide fine particles or ceramic fine particles with a vacuum defoaming mixer such as Avatori Mixer ARV-310P manufactured by THINKY or a planetary mixer can be used. In this case, the speed of sound in the finished material can be adjusted by adjusting the total number of fine particles kneaded into the resin material.

For example, iron, tungsten, alumina, zirconia, silica, or the like can be used as the material of the fine particles. In order to reduce the attenuation of ultrasonic waves in the first acoustic matching layer 4 to the fourth acoustic matching layer 7, the fine particles preferably have a diameter of 0.01 μm or more and 100.00 μm or less, and 0.10 μm or more. More preferably, it has a diameter of 10.00 μm or less.

Further, the resonance frequency in the width direction of the acoustic matching piece 4A, that is, the resonance frequency caused by the width L1 is set at the high frequency side of the frequency band A1 of the piezoelectric element 3 at a sensitivity of −20 dB in order to obtain a high-definition ultrasonic image, for example. However, if it is higher than the frequency on the high frequency side in the frequency band that takes at least half the amplitude value of the resonance frequency in the thickness direction of the piezoelectric element 3, the high frequency can be obtained without degrading the image quality. A fine ultrasound image can be obtained. Further, the resonance frequency caused by the width L1 of the acoustic matching piece 4A is higher than the frequency on the high frequency side in the frequency band having a value of 1/10 of the amplitude of the resonance frequency in the thickness direction of the piezoelectric element 3. It is more preferable from the viewpoint of obtaining a high-definition ultrasonic image without lowering the .

The resonance frequency caused by the width L2 of the acoustic matching piece 4B is also in a frequency band that takes at least half the amplitude value of the resonance frequency in the thickness direction of the piezoelectric element 3, similarly to the resonance frequency caused by the width L1 of the acoustic matching piece 4A. is preferably higher than the frequency on the high frequency side in the thickness direction of the piezoelectric element 3, and more preferably higher than the frequency on the high frequency side in the frequency band having a value of 1/10 of the amplitude of the resonance frequency in the thickness direction of the piezoelectric element 3.

In order to obtain a high-quality ultrasound image, even at a sensitivity of -6 dB or the like, which is used when generating a normal ultrasound image, rather than when generating a high-definition ultrasound image, acoustic matching The resonance frequency caused by the width L1 of the piece 4A and the resonance frequency caused by the width L2 of the acoustic matching piece 4B are preferably higher than the frequency on the high frequency side of the frequency band A1 in the thickness direction of the piezoelectric element 3 .

Also, the width L1 of the acoustic matching piece 4A and the width L2 of the acoustic matching piece 4B of the first acoustic matching layer 4 can have the same length, but can also have different lengths. Even in this case, the width L1 of the acoustic matching piece 4A and the width L2 of the acoustic matching piece 4B are narrower than the width of the piezoelectric element 3 in the Y direction. The resonance frequency caused by the width L2 of 4B can be made higher than the frequency on the high frequency side of the frequency band A1 of the piezoelectric element 3 .

Also, although it is described that the first acoustic matching layer 4 is composed of two

acoustic matching pieces

4A and 4B, the first acoustic matching layer 4 includes three or more pieces arranged side by side in the Y direction. of acoustic matching pieces. When the first acoustic matching layer 4 has three or more acoustic matching pieces, compared to the case where the first acoustic matching layer 4 has two

acoustic matching pieces

4A and 4B, Since the width of each acoustic matching piece in the Y direction can be narrowed, the resonance frequency caused by the width of each acoustic matching piece in the Y direction can be made higher than the frequency on the high frequency side of the frequency band A1 of the piezoelectric element 3. can.

Also, the first acoustic matching layer 4 can be composed of a plurality of acoustic matching pieces arranged in the Y direction and the X direction, respectively, as shown in FIG. 7, for example. In the example of FIG. 7, the first acoustic matching layer 41 has a plurality of square prism-shaped acoustic matching pieces 41A. A plurality of acoustic matching pieces 41A are arranged with gaps in the X direction and the Y direction.

Also, the gaps between the plurality of acoustic matching pieces 41A can be filled with a filler similar to the filler SP.

Further, as shown in FIG. 8, for example, the first acoustic matching layer 42 may be composed of a plurality of cylindrical acoustic matching pieces 42A.
In FIGS. 7 and 8, the shapes of the

acoustic matching pieces

41A and 42A are exemplified by a square prism shape and a cylindrical shape. Any cone-shaped acoustic matching piece, such as a regular polygonal pyramid or a cone, may be used. An acoustic matching piece having such a shape can be formed by a technique such as etching, for example.

The number of acoustic matching pieces constituting the first acoustic matching layers 4, 41 and 42 is particularly limited if the width of the acoustic matching pieces in the Y direction is narrower than the width of the piezoelectric element 3 in the Y direction. not a thing

Also, the plurality of acoustic matching pieces of the first acoustic matching layers 4, 41 and 42 may be arranged to have patterns as shown in FIGS. 9 to 11 when viewed from the +Z direction. good. In the example shown in FIG. 9, a plurality of square prism-shaped acoustic matching pieces 51 are arranged in a staggered manner in the X direction. In the example shown in FIG. 10, a plurality of equilateral triangular prism-shaped acoustic matching pieces 52 are arranged so as to be closely packed in the XY plane. In the example shown in FIG. 11, a plurality of regular hexagonal prismatic acoustic matching pieces 53 are arranged so as to be closely packed in the XY plane, forming a so-called honeycomb pattern.

Further, among the plurality of first acoustic matching layers 4, 41 or 42 arranged in the Y direction of the ultrasound probe 1, each of the first acoustic matching layers 4, 41 or 42 has a plurality of acoustic matching layers. It can be designed to vary the sum of the Y-direction widths of the strips. Thereby, the speed of sound of the ultrasonic waves emitted from the ultrasonic probe 1 can be locally adjusted in the Y direction. As a result, the ultrasonic probe 1 can be acoustically designed in a wide variety of ways.

Also, the first acoustic matching layers 4, 41, and 42 located in the center of the X direction of the ultrasonic probe 1 have a plurality of acoustic matching pieces arranged relatively densely in the X direction, and the ultrasonic probe A plurality of acoustic matching pieces can be arranged relatively sparsely in the X direction in the first acoustic matching layers 4, 41 and 42 positioned at both ends of the X direction. As a result, like a so-called apodization method, the emission of the ultrasonic beams emitted from both ends of the ultrasonic probe 1 in the X direction is suppressed, the ultrasonic beams are narrowed, and the X direction of the ultrasonic probe 1 is suppressed. It is possible to reduce so-called side lobes in which ultrasonic beams are emitted in directions deviating from the center of the .

Further, it is described that only the first acoustic matching layer 4 among the first acoustic matching layer 4 to the fourth acoustic matching layer 7 is composed of a plurality of acoustic matching pieces. At least one of the matching layer 4 to the fourth acoustic matching layer 7 may be composed of a plurality of acoustic matching pieces. However, since the first acoustic matching layer 4 located closest to the piezoelectric element 3 is made of a material having a higher acoustic impedance than the second acoustic matching layer 5 to the fourth acoustic matching layer 7, the first From the viewpoint of obtaining a high-quality ultrasound image, it is most preferable that the acoustic matching layer 4 is composed of a plurality of acoustic matching pieces.

In addition, although the ultrasonic probe 1 has been described as having four acoustic matching layers, the first acoustic matching layer 4 to the fourth acoustic matching layer 7, it has five or more acoustic matching layers. can also The more acoustic matching layers the ultrasonic probe 1 has, the more the acoustic matching layers placed closer to the piezoelectric element 3 need to be made of a material with a higher acoustic impedance. It is considered that the resonance frequency caused by the width of the acoustic matching piece in the Y direction tends to approach the frequency band A1 of the piezoelectric element 3 when the matching piece is used. In the ultrasonic probe 1 of the present invention, the width of the acoustic matching piece in the Y direction is narrower than the width of the piezoelectric element 3 in the Y direction. The more acoustic matching layers the ultrasonic probe 1 has, the more useful it is because the frequency bands due to the width can be separated from each other.

Also, although the transmitter/receiver 12 is described as being included in the processor 22, it can also be configured by an electric circuit.
Also, the transmitter/receiver 12 may be included in the ultrasonic probe 21 .
As described above, regardless of whether the transmitting/receiving unit 12 is configured by an electric circuit or is included in the ultrasonic probe 21, the ultrasonic diagnostic apparatus 11 according to the embodiment of the present invention Since the ultrasonic probe 1 is provided, the frequency band of ultrasonic waves transmitted from the ultrasonic probe 1 to the subject by the transmitting/receiving unit 12 and the frequency of the ultrasonic waves received by the ultrasonic probe 1 A high-quality ultrasound image can be obtained while widening the band.

1 Ultrasonic probe 2 Backing material 3

Piezoelectric element

4, 41, 42 First

acoustic matching layer

4A, 4B, 41A, 42A, 51, 52, 53 Acoustic matching piece 5 Second acoustic matching layer, 6 third acoustic matching layer, 7 fourth acoustic matching layer, 8 acoustic lens, 11 ultrasonic diagnostic apparatus, 12 transmission/reception circuit, 13 image generation unit, 14 display control unit, 15 monitor, 16 device control unit, 17 Input device, 21 Ultrasound probe, 22 Processor, 31 Pulser, 32 Amplifier, 33 AD converter, 34 Beamformer, 35 Signal processor, 36 DSC, 37 Image processor, A1, A2, A3 Frequency band, L1 , L2 width, SP filler.

Claims

An ultrasonic probe in which a plurality of piezoelectric elements are arranged along the arrangement direction on a backing material,
A plurality of acoustic matching layers laminated on each of the piezoelectric elements,
At least one acoustic matching layer among the plurality of acoustic matching layers is an ultrasonic probe comprising at least one acoustic matching piece having a width narrower than the width of the piezoelectric elements in the arrangement direction.
The ultrasonic probe according to claim 1, wherein the at least one acoustic matching layer is the acoustic matching layer closest to the piezoelectric element among the plurality of acoustic matching layers.
The ultrasonic probe according to claim 1 or 2, wherein the plurality of acoustic matching layers are composed of four or more acoustic matching layers, the acoustic impedance of which decreases stepwise as the distance from the piezoelectric element increases.
4. The acoustic matching piece according to any one of claims 1 to 3, wherein the resonance frequency in the width direction of the acoustic matching piece is higher than the frequency on the high frequency side in a frequency band that takes at least half the amplitude value of the resonance frequency in the thickness direction of the piezoelectric element. An ultrasonic probe as described.
5. The ultrasonic wave according to claim 4, wherein the resonance frequency in the width direction of the acoustic matching piece is higher than the frequency on the high frequency side in a frequency band having a value of 1/10 of the amplitude value of the resonance frequency in the thickness direction of the piezoelectric element. probe.
The ultrasonic probe according to any one of claims 1 to 5, wherein said at least one acoustic matching layer comprises a plurality of said acoustic matching pieces arranged in said arrangement direction.
The ultrasonic probe according to claim 6, wherein said at least one acoustic matching layer comprises a plurality of said acoustic matching pieces arranged in said arrangement direction and in a direction orthogonal to said arrangement direction.
The ultrasonic probe according to claim 7, wherein the acoustic matching piece has any shape of a polygonal column, a cylinder, a polygonal pyramid, and a cone extending in the stacking direction of the plurality of acoustic matching layers.
The ultrasonic probe according to any one of claims 6 to 8, wherein a resin filler is arranged between the plurality of acoustic matching pieces.